The joyful feast of Our Redeemer's triumphant Ascension should cause us to focus on heavenly things. We offer an explanation on the Mass propers for the Feast of the Ascension of Our Lord Jesus Christ into Heaven. (from The Church's Year, Fr. Leonard Goffine)
At the Introit the Church sings the words which were spoken by the angels to the apostles and disciples, after the Ascension of our Lord:
Ye men of Galilee, why wonder you, looking up to heaven? Alleluia: He shall so come as you have seen him going up into heaven. Alleluia, alleluia, alleluia. (Acts 1:11), Oh, clap your hands, all ye nations; shout unto God with the voice of joy. (Ps. 46:2) Glory be to the Father, etc.
Grant, we beseech Thee, O Almighty God, that we who believe Thy only-begotten Son, our Redeemer, to have this day ascended into the heavens, may ourselves also in, mind dwell amid heavenly things. Through the same, etc.
Epistle (Acts 1:1-11)
The former treatise I made, O Theophilus, of all things which Jesus began to do and to teach, until the day on which, giving commandments by the Holy Ghost to the apostles, whom he had chosen, he was taken up: to whom also he showed himself alive after his passion, by many proofs, for forty days appearing to them, and speaking of the kingdom of God. And eating together with them, he commanded them that they should not depart from Jerusalem, but should wait for the promise of the Father, which you have heard (saith he) by my mouth: for John indeed baptized with water, but you shall be baptized with the Holy Ghost, not many days hence.
They, therefore, who were come together, asked him, saying: Lord, wilt thou at this time restore the kingdom to Israel? But he said to them: It is not for you to know the times or moments which the Father hath put in his own power; but you shall receive the power of the Holy Ghost coming upon you, and you shall be witnesses to me in Jerusalem and in all Judea, and Samaria, and even to the uttermost part of the earth.
And when he had said these things, while they looked on, he was raised up; and a cloud received him out of their sight. And while they were beholding him going up to heaven, behold, two men stood by them in white garments, who also said: Ye men of Galilee, why stand yon looking up to heaven? This Jesus who is taken up from you into heaven, shall so come, as you have seen him going into heaven.
This Gospel of St. Luke addressed to Theophilus, a Christian of note in Antioch, contains an account of the life, sufferings, and death of Jesus up to the time of His Ascension into heaven. The Evangelist continues his account in the Acts of the Apostles, in which he describes in simple words that which Jesus did during the forty days following His Resurrection, and the manner in which He ascended into heaven in the presence of His apostles. Rejoice that Christ today has entered into the glory gained by His sufferings and death, and pray:
I rejoice, O King of heaven and earth, in the glory Thou hast this day attained in heaven. Sing to God, ye kingdoms of the earth: sing ye to the Lord: sing ye to God, who mounteth above the heaven of heavens to the east. Give ye glory to God for Israel, his magnificence and his power is in the clouds. God is wonderful in his saints, the God of Israel is he who will give power and strength to his people, blessed be God." (Ps. 67:33‑36)
Gospel (Mark 16:14-20)
At that time, Jesus appeared to the eleven as they were at table: and he upbraided them with their incredulity and hardness of heart, because they did not believe them who had seen him after he was risen again.
And he said to them: Go ye into the whole world, and preach the gospel to every creature. He that believeth and is baptized shall be saved: but he that believeth not shall be condemned: And these signs shall follow them that believe. In my name they shall cast out devils: they shall speak with new tongues; they shall take up serpents: and if they shall drink any deadly thing, it shall not hurt them: they shall lay their hands upon the sick; and they shall recover.
And the Lord Jesus after he had spoken to them, was taken up into heaven, and sitteth on the right hand of God. But they going forth preached everywhere, the Lord working withal, and confirming the word with signs that followed.
Musical recommendation: listen to a polyphonic version of the Introit's words by Giovanni Pierluigi da Palestrina; Viri Galilaei.
Viri Galilaei, quid statis aspicientes in cælum?
Ye men of Galilee, why stand you looking up to heaven?
Hic Jesus, qui assumptus est a vobis in cælum,
This Jesus who is taken up from you into heaven,
Sic veniet, quemadmodum vidistis eum euntem in cælum. Alleluia.
Shall so come as you have seen him going into heaven.
Ascendit Deus in jubilatione, et Dominus in voce tubae. Alleluia.
God is ascended with jubilee, and the Lord with the sound of trumpet. Alleluia.
Dominus in cælo paravit sedem suam. Alleluia.
The Lord hath prepared his throne in heaven. Alleluia.